The long term goal of this research is to understand from a cellular and molecular perspective how neurons achieve the subcellular targeting of proteins required for polarized flow of information. The specific focus is to elucidate mechanisms underlying targeting of metabotropic glutamate receptors (mGluRs) to somatodendritic or axonal domains. Preliminary studies expressing epitope tagged mGluRs from defective herpesvirus vectors in cultured hippocampal neurons have shown that mGluR1a and mGluR2 target to dendrites whereas mGluR7 targets to both dendrites and axons. Expression of chimeric and deletion constructs was used to demonstrate the C-terminal domains within mGluR2 and mGluR7 are required for axon exclusion versus axon targeting. Aim 1 of this proposal is determine whether addition of these mGluR signals can redirect unrelated neuronal plasma membrane proteins to or from the axon, and to begin to define domains that mediate synaptic clustering of mGluR7. Aim 2 will define cellular mechanisms of axon/dendrite targeting by visualizing vesicle populations and trafficking patterns. Aim 3 will determine underlying molecular mechanisms. Part A will test the longstanding hypothesis that the major (-) end direct microtubule motor, dynein, mediates specific transport into dendrites. Part B will identify proteins that interact with the mGluR targeting signals. Such interacting proteins are likely to include sorting receptors or vesicle adaptor coat proteins and domain specific anchoring or stabilizing proteins. These aims represent major steps towards the long term goal to understand cellular trafficking pathways for polarized neuronal membrane proteins and isolate and characterize underlying molecular components. From a clinical perspective, regeneration of neuronal polarity is critical in recovery from injury, and aberrations in subcellular trafficking are central features of Alzheimer's disease. mGluRs can play a neuroprotective role, and so understanding their cell biology may contribute to therapies for neurological disorders. Finally, the identification of short axonal and dendritic targeting modules that can redirect heterologous proteins will be immediately applicable to controlling protein localization in experimental and gene therapy studies.